The storage of hydrocarbon fluids in underground caverns in salt beds is generally well known. See for example U.S. Pat. No. 3,253,414 which discloses the storage of a hydrocarbon fluid with a density lower than that of liquid brine in such a cavern.
When hydrocarbon fluid is pumped into a storage cavern, brine is forced out of the cavern to the surface where it may be stored in a brine pit. Conventionally this removed brine is passed to a liquid-gas disengagement vessel prior to storage in the pit. The liquid-gas disengagement vessel effects the separation of any hydrocarbon present in the brine. The separated hydrocarbon, as a gas or vapor, is normally charged to a flare means and the degassed brine is charged to a brine pit or pond where it remains available for reuse; e.g. to be pumped back into the cavern to effect removal of hydrocarbon.
The liquid brine in the relatively high pressure storage cavern is saturated with the light hydrocarbon stored over the brine. When the brine is removed from the cavern, two phase flow occurs along the removal flow path. The two phase flow comprises hydrocarbon gas bubbles and liquid brine. These gaseous hydrocarbon bubbles are relatively large at the downstream portion of the flow path since the pressure there is only slightly above atmospheric.
In prior operations this two phase flow of gaseous hydrocarbon and liquid brine has been charged directly into a liquid-vapor disengaging drum. The effect of the large gaseous hydrocarbon bubbles disengaging from the drum cause surging of the fluid to the flare. The result is an ecologically undesirable smokey flare.